Method for the continuous separation by distillation of mixtures that contain morphonline (MO), monoaminodiglycol (ADG), ammonia and water by means of distillation

ABSTRACT

Processes for the continuous fractional distillation of a mixture containing morpholine (MO), monoaminodiglycol (ADG), ammonia and water from a reaction of diethylene glycol (DEG) with ammonia, the process including: (i) separating off ammonia from the mixture at a top of a first distillation column K 10 ; (ii) feeding a bottom fraction from K 10  to a second distillation column K 20 , in which water and an organic product are separated off at the top at a temperature at the top in the range from 45 to 198° C. and a pressure in the range from 0.1 to 15 bar; (iii) feeding a bottom fraction from K 20  to a third distillation column K 30 , wherein the column K 30  is a dividing wall column (DWC)which preferably has a dividing wall (DW) in the longitudinal direction of the column to form an upper combined column region ( 1 ), a lower combined column region ( 6 ), an inflow part ( 2,4 ) having an enrichment section ( 2 ) and a stripping section ( 4 ), and also an offtake part ( 3,5 ) having an enrichment section ( 3 ) and a stripping section ( 5 ), with the bottoms from K 20  being fed in in the upper or middle third of the inflow part ( 2,4 ), based on the number of theoretical plates of the inflow part, ADG and organic products having a boiling point of &gt;190° C. (1.013 bar) being discharge at the bottom, organic products having a boiling point of ≦128° C. (1.013 bar) being discharge at a top and MO being discharge from the middle or lower third of the offtake part ( 3,5 ) (side offtake), based on the number of theoretical plates of the offtake part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application, under 35 U.S.C. §371,of PCT/ EP2007/059557, filed Sep. 12, 2007, which claims benefit ofEuropean Patent Application No. 06121428.4, filed Sep. 28, 2006.

BACKGROUND OF THE INVENTION

Aminodiglycol (ADG) [=2-(2-aminoethoxy)ethanol=2,2′-aminoethoxyethanol,formula

and morpholine are used, inter alia, as solvents, stabilizers, for thesynthesis of chelating agents, synthetic resins, drugs, inhibitors andsurface-active substances. N-Ethylmorpholine (E-MO) is used, inter alia,as catalyst for the production of polyurethane foams.

Numerous methods of preparing ADG and morpholine are described in theliterature.

Ullmann's Encyclopedia of Industrial Chemistry, 6th Edition, 2000electronic release, Wiley-VCH Verlag, Rubrik ‘cyclic amines’ in thechapter ‘aliphatic amines’, describes the synthesis of ADG and MO byamination of DEG under hydrogen pressure and in the presence of a cobaltor nickel catalyst (citations: EP-A-696 572 (BASF AG), DE-A-1 049 864)or other catalysts (citations: DE-A-3 002 342, DE-A-3 125 662 (BASF AG),U.S. Pat. No. 3,155,657).

The earlier German patent application No. 102005047458.6 of Sep. 30,2005 and the earlier European (subsequent) patent application No.06101339.7 of Feb. 6, 2006 (BASF AG) relate to a process for preparingADG and morpholine by reaction of DEG with ammonia in the presence of aspecific copper, nickel and cobalt heterogeneous catalyst and also ingeneral terms the work-up by multistage distillation.

Two parallel European patent applications having the same filing date(both BASF AG) relate to processes for the continuous fractionaldistillation of mixtures comprising morpholine (MO), monoaminodiglycol(ADG), ammonia and water obtained by reaction of diethylene glycol (DEG)with ammonia.

A parallel European patent application having the same filing date (BASFAG) relates to a process for preparing electronics-grade ADG.

The synthesis of morpholine and monoaminodiglycol is notable for theformation of many secondary components. Unreacted starting materials,products of value and the by-products are separated off by distillation,which leads to a considerable outlay in terms of apparatus and energy.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a process for the continuous fractionaldistillation of mixtures comprising morpholine (MO), monoaminodiglycol(ADG), ammonia and water obtained by reaction of diethylene glycol (DEG)of the formula

with ammonia.

It was an object of the present invention to overcome a disadvantage ora number of disadvantages of the prior art and discover an improvedeconomical process for the fractionation of mixtures comprisingmorpholine (MO), monoaminodiglycol (ADG), ammonia and water and possiblyN-ethylmorpholine (E-MO) and possibly 1,2-ethylenediamine (EDA) andpossibly organic products having a boiling point of >224.8° C. (1.013bar). The individual organic components (amines), in particular MO andADG and possibly E-MO, should be obtained in high purity and quality(e.g. color quality).

We have accordingly found a process for the continuous fractionaldistillation of mixtures comprising morpholine (MO), monoaminodiglycol(ADG), ammonia and water obtained by reaction of diethylene glycol (DEG)with ammonia, which comprises

-   separating off ammonia at the top of a first distillation column    K10,-   feeding the bottoms from K10 to a second distillation column K20 in    which water and organic products are separated off at the top at a    temperature at the top in the range from 45 to 198° C. and a    pressure in the range from 0.1 to 15 bar,-   feeding the bottoms from K20 to a third distillation column K30,    wherein the column K30 is a dividing wall column (DWC) which    preferably has a dividing wall (DW) in the longitudinal direction of    the column to form an upper combined column region (1), a lower    combined column region (6), an inflow part (2, 4) having an    enrichment section (2) and a stripping section (4), and also an    offtake part (3, 5) having an enrichment section (3) and a stripping    section (5), with the bottoms from K20 being fed in in the upper or    middle third, particularly preferably the upper third, of the inflow    part (2, 4), based on the number of theoretical plates of the inflow    part, ADG and organic products having a boiling point of >190° C.    (1.013 bar) being discharged at the bottom, organic products having    a boiling point of ≦128° C. (1.013 bar), preferably <128° C. (1.013    bar), being discharged at the top and MO being discharged from the    middle or lower third, particularly preferably the lower third, of    the offtake part (3, 5) (side offtake), based on the number of    theoretical plates of the offtake part.

DETAILED DESCRIPTION OF THE INVENTION

The column K10 preferably has from 3 to 30, particularly preferably from5 to 20, theoretical plates.

It is preferably operated at a pressure in the range from 5 to 30 bar,particularly preferably from 10 to 20 bar.

The feed point of column K10 is preferably located in the upper third,based on the number of theoretical plates.

The column K20 preferably has from 25 to 70, particularly preferablyfrom 30 to 60, theoretical plates.

It is preferably operated at a pressure in the range from 0.1 to 10 bar,particularly preferably from 0.8 to 7 bar.

The feed point of column K20 is preferably located in the middle third,based on the number of theoretical plates.

Water is preferably separated off in the column K20. Organic products,some of which have boiling points higher than that of the bottom productmorpholine, are preferably separated off at the top together with thiswater as a minimum-boiling azeotrope.

The dividing wall column K30 preferably has from 30 to 100, particularlypreferably from 40 to 90, theoretical plates.

It is preferably operated at a pressure in the range from 0.01 to 5 bar,particularly preferably from 0.1 to 2.5 bar.

The organic products separated off at the top of the column K30, inparticular EDA, can advantageously be recirculated in their entirety orin part to the feed to the column K20.

In a further embodiment, pure EDA can be obtained as product of value byfurther purification by distillation of the overhead distillate fromK30.

The subregion of the column (DWC) divided by the dividing wall (DW) andcomprising the subregions 2, 3, 4 and 5 or parts thereof is preferablyprovided with ordered packing, random packing elements and/or trays. Thedividing wall in these subregions is preferably thermally insulating.

In a particular embodiment, the stream comprising water and organicproducts which is separated off at the top of the column K20 is fed to acolumn K50 in which aqueous N-ethylmorpholine solution (aqueous E-MOsolution) is separated off at the top or at a side offtake for liquid,with the side offtake for liquid preferably being located in the upperthird of the column, based on the number of theoretical plates, andwater is separated off at the bottom.

The column K50 preferably has from 10 to 50, particularly preferablyfrom 15 to 40, theoretical plates.

It is preferably operated at a pressure in the range from 0.1 to 16 bar,particularly preferably from 0.2 to 8 bar.

The feed point of column K50 is preferably located in the upper ormiddle third, particularly preferably in the middle third, based on thenumber of theoretical plates.

To isolate pure E-MO, the aqueous N-ethylmorpholine solution is firstlydewatered. As dewatering agent, preference is given to using sodiumhydroxide, e.g. as a 40-60% strength by weight aqueous solution,particularly preferably a 50% strength by weight aqueous solution. Thedewatering using the sodium hydroxide is preferably carried outcontinuously in an extraction column. The extraction temperature ispreferably 25-60° C., particularly preferably 30-55° C. The sodiumhydroxide solution is diluted to 15-35% by weight, particularlypreferably 20-30% by weight, during the extraction.

After phase separation, the organic phase is worked up in a continuousor batch distillation. The distillation is preferably carried outbatchwise in a still pot.

In this case, the overhead products are obtained in succession:ethylamine if present, possibly ethanol as aqueous azeotrope, possiblyN-methylmorpholine as aqueous azeotrope, possibly water-freeN-methylmorpholine and the desired product N-ethylmorpholine (E-MO).

In a preferred embodiment, the bottoms from K30 are fed to adistillation column K60 in which ADG is separated off at a side offtake,organic products having a boiling point of ≦224.8° C. (1.013 bar) areseparated off at the top and organic products having a boiling pointof >255° C. (1.013 bar) are separated off at the bottom.

The column K60 preferably has from 20 to 80, particularly preferablyfrom 30 to 70, theoretical plates.

It is preferably operated at a pressure in the range from 0.005 to 1bar, particularly preferably from 0.01 to 0.7 bar.

The feed point of column K60 is preferably located in the middle orlower third, particularly preferably the middle third, based on thenumber of theoretical plates. The ADG side offtake located opposite thefeed point is preferably located from 1 to 30, particularly preferablyfrom 2 to 20, theoretical plates above the feed point.

In a preferred embodiment, organic products separated off at the top ofthe column K60, e.g. N-(2-aminoethyl)morpholine,2-(2-aminoethoxy)ethylamine, are recirculated to the reaction of DEGwith ammonia.

To avoid accumulation of individual components in the circuit of theproduction plant, a, substream of the distillate separated off at thetop of the column is preferably discharged. The proportion of therecirculated stream is preferably 40-100% by weight, particularlypreferably 50-100% by weight, of the distillate separated off at the topof the column.

The organic products separated off at the bottom of the column K60 canadvantageously be used as milling aids in the cement industry.

The ADG-comprising stream separated off at the side offtake of thecolumn K60 is preferably fed to a column K70 in which ADG is separatedoff at a side offtake, organic products having a boiling point of≧224.8° C. (1.013 bar), particularly preferably >235° C. (1.013 bar),are separated off at the bottom and organic products having a boilingpoint of ≦224.8° C. (1.013 bar) are separated off at the top.

The column K70 preferably has from 10 to 80, particularly preferablyfrom 20 to 70, theoretical plates.

It is preferably operated at a pressure in the range from 0.005 to 1bar, particularly preferably from 0.01 to 0.7 bar.

The feed point of column K70 is preferably located in the upper ormiddle third, preferably the middle third, based on the number oftheoretical plates.

The ADG side offtake located opposite the feed point is preferablylocated from 1 to 30, particularly preferably from 2 to 25, theoreticalplates above the feed point.

Products separated off at the bottom of column K70, e.g. DEG,

-   morpholylaminodiglycol, morpholinodiglycol, are preferably    recirculated to the reaction of DEG with ammonia.-   (Morpholylaminodiglycol=4-(2-(2-aminoethoxy)ethyl)morpholine,    C₈H₁₈N₂O₂; morpholinodiglycol (morpholinylethoxyethanol) CAS No.    3603-45-0, C₈H₁₇NO₃)

Products separated off at the top of column K70, e.g. ADG,N-(2-aminoethyl)morpholine, 2-(2-aminoethoxy)ethylamine, are preferablyrecirculated to the reaction of DEG with ammonia.

The proportion of the recirculated stream is preferably 80-100% byweight, particularly preferably 95-100% by weight, of the distillateseparated off at the top of the column.

In a further particularly preferred embodiment, the column K60 is adividing wall column (DWC2).

The dividing wall column (DWC2) preferably has a dividing wall (DW) inthe longitudinal direction of the column to form an upper combinedcolumn region (1), a lower combined column region (6), an inflow part(2, 4) having an enrichment section (2) and a stripping section (4), andalso an offtake part (3, 5) having an enrichment section (3) and astripping section (5), with the bottoms from K30 being fed in in theupper or middle third, particularly preferably the upper third, of theinflow part (2, 4), based on the number of theoretical plates of theinflow part, organic products having a boiling point of >255° C. (1.013bar) being discharged at the bottom, organic products having a boilingpoint of ≦224.8° C. (1.013 bar) being discharged at the top, ADG beingdischarged from the column region 1 and optionally, in a particularembodiment preferably, gaseous organic products having a boiling pointof ≧224.8° C. (1.013 bar), particularly preferably >235° C. (1.013 bar),e.g. DEG, being discharged from the upper or middle third, particularlypreferably the upper third, of the offtake part (3, 5) (side offtake),based on the number of theoretical plates of the offtake part.

Organic products separated off in gaseous form at the side offtake ofthe column K60, e.g. DEG, are preferably recirculated to the reaction ofDEG with ammonia.

In a further advantageous embodiment, the dividing wall column (DWC2)has a dividing wall (DW) in the longitudinal direction of the column toform an upper combined column region (1) and (2), an inflow part (3, 4)having an enrichment section (3) and a stripping section (4), and also apart (5), with the dividing wall DW extending to the bottom of thecolumn and the bottoms from K30 being fed in in the upper or middlethird, particularly preferably the upper third, of the inflow part (3,4), based on the number of theoretical plates of the inflow part, DEGand organic products having a boiling point of ≧224.8° C. (1.013 bar),preferably >235° C. (1.013 bar), being discharged at the bottom belowthe part 5, organic products having a boiling point of >255° C. (1.013bar) (high boilers=HB) being discharged at the bottom below the parts 3and 4, organic products having a boiling point of ≦224.8° C. (1.013 bar)being discharged at the top and ADG being discharged from the middlepart of the upper combined column region (1) and (2) (side offtake).

The dividing wall column K60 preferably has from 30 to 100, particularlypreferably from 40 to 90, theoretical plates.

It is preferably operated at, a pressure in the range from 0.005 to 1bar, particularly preferably from 0.01 to 0.7 bar.

The subregion of the column (DWC2) divided by the dividing wall (DW) andcomprising the subregions 3, 4 and 5 or 2, 3, 4 and 5 or in each caseparts thereof is preferably provided with ordered packing, randompacking elements and/or trays. The dividing wall in these subregions ispreferably thermally insulating.

In a preferred embodiment, organic products separated off at the top ofthe column K60, e.g. N-(2-aminoethyl)morpholine,2-(2-aminoethoxy)ethylamine, are not discharged from the process but arerecirculated to the reaction of DEG with ammonia.

Organic products separated off at the bottom below the part 5 of columnK60 having a dividing wall DW extending to the bottom of the column,e.g. DEG, are preferably recirculated to the reaction of DEG withammonia.

The proportion of the recirculated stream is preferably 80-100% byweight, particularly preferably 95-100% by weight, of the distillateseparated off at the top of the column.

In particular embodiments using the further dividing wall column (DWC2),the process of the invention also advantageously displays an even lowerheat requirement compared to the 2- or 3-column arrangement (K60-K70 orK80) and a further reduced number of columns.

In a particular embodiment of the process of the invention, theADG-comprising stream/streams separated off at the top of the columnsK60 and/or K70 is/are fed in its/their entirety or in part to a columnK80 in which ADG and organic products having a boiling point of ≧224.8°C. (1.013 bar) are separated off at the bottom and organic productshaving a boiling point of ≦224.8° C. (1.013 bar) are separated off atthe top.

The ADG obtained at the bottom can be utilized as product of value.

ADG in particularly pure form is preferably additionally separated offat a side offtake of the column K80.

In this case, products separated off at the bottom of column K80 arepreferably recirculated to the feed to the columns K60 and/or K70.

Products separated off at the top of column K80 are preferablyrecirculated to the reaction of DEG with ammonia.

To avoid accumulation of individual components in the circuit of theproduction plant, a substream of the distillate separated off at the topof the column is preferably discharged. The proportion of therecirculated stream is preferably 0-100% by weight, particularlypreferably 0-50% by weight, of the distillate separated off at the topof the column.

The column K80 preferably has from 10 to 80, particularly preferablyfrom 15 to 60, theoretical plates.

It is preferably operated at a pressure in the range from 0.005 to 3bar, particularly preferably from 0.01 to 2 bar.

The feed point of column K80 is preferably located in the upper ormiddle third, preferably the upper third, based on the number oftheoretical plates.

The ADG side offtake located opposite the feed point is preferablylocated from 1 to 30, particularly preferably from 2 to 25, theoreticalplates below the feed point.

In particular embodiments, the process of the invention is additionallyadvantageous as a result of the following heat integration measures:

The heat from the vapor from K80 can be integrated into K50.

The heat from the vapor from K70 can be integrated into K50 and/or K80,preferably K50.

The heat from the vapor from K60 can be integrated into K50.

The heat from the vapor from the dividing wall column K60 can beintegrated into K50.

This heat integration can be effected as follows:

To be able to make maximum use of the heat obtained from the vapor, aheat transfer medium is preferably dispensed with and the vapor streamsare preferably condensed directly in the corresponding vaporizersinstead of heating steam. As vaporizers, it is in each case possible touse natural convection vaporizers, forced circulation vaporizers, forcedcirculation depressurization vaporizers, falling film evaporators,Robert evaporators, kettle-type vaporizers, thin film evaporators orclimbing film evaporators. Preference is in each case given to usingnatural convection vaporizers, forced circulation vaporizers, forcedcirculation depressurization vaporizers, falling film evaporators,Robert evaporators or kettle-type vaporizers.

The residual vapors are preferably in each case liquefied in anafter-condenser.

Furthermore, it is advantageous for the heat of reaction from thesynthesis of the mixture to be fractionated to be removed, in particularby evaporative cooling (steam), and integrated into the distillation.Embodiments (A) and (B) are particularly preferred in the synthesis.

The heat of reaction can here be integrated into the columns K20, K50,K30, K70 and/or K80, preferably into the columns K20, and/or K80.

The mixture comprising morpholine (MO), monoaminodiglycol (ADG), ammoniaand water, and possibly E-MO and possibly EDA and possibly organicproducts having a boiling point of >224.8° C. (1.013 bar) which is usedin the process of the invention has, in an embodiment (A), preferablybeen obtained by reaction of diethylene glycol (DEG) with ammonia in thepresence of a catalyst comprising Cu, Ni and Co on zirconium dioxide assupport.

Catalysts of this type are described in EP-A-963 975, EP-A-1 106 600 andWO-A-03/076386 (all BASF AG).

In a particularly preferred catalyst, the catalytically activecomposition of the catalyst before treatment with hydrogen comprisesfrom 20 to 65% by weight of zirconium dioxide (ZrO₂), from 1 to 30% byweight of oxygen-comprising compounds of copper, calculated as CuO, from15 to 50% by weight of oxygen-comprising compounds of nickel, calculatedas NiO, and from 15 to 50% by weight of oxygen-comprising compounds ofcobalt, calculated as CoO.

The temperature in the reactor which is preferred for the reaction ofdiethylene glycol (DEG) with ammonia is in the range from 170 to 220° C.Preference is given to isothermal operation of the reactor. The pressurepreferred for the reaction of diethylene glycol (DEG) with ammonia is inthe range from 100 to 200 bar.

The reaction of diethylene glycol (DEG) with ammonia is preferablycarried out in the presence of hydrogen. The hydrogen is preferablyrecirculated as recycle gas via a high-pressure separator to thereactor.

The molar ratio of ammonia:DEG is preferably in the range from 4 to 6.

The DEG conversion is preferably in the range from 55 to 90%.

The mixture used in the process of the invention is particularlypreferably produced as described in the earlier German patentapplication No. 102005047458.6 of Sep. 30, 2005 and the earlier European(subsequent) patent application No. 06101339.7 of Feb. 6, 2006 (BASFAG), according to which the reaction of DEG with ammonia is carried outin the presence of a specific shaped catalyst body and the catalyticallyactive composition of the catalyst before treatment with hydrogencomprises oxygen-comprising compounds of aluminum and/or zirconium,copper, nickel and cobalt.

In another embodiment (B), the mixture comprising morpholine (MO),monoaminodiglycol (ADG), ammonia and water, and possibly E-MO andpossibly EDA and possibly organic products having a boiling pointof >224.8° C. (1.013 bar), which is used in the process of the inventionhas preferably been obtained by reaction of diethylene glycol (DEG) withammonia in the presence of a catalyst comprising Cu and Ni on aluminumoxide as support, as described, in particular, in EP-A-70 397 (BASF AG).

Catalysts of this type are also described in EP-A-514 692 and EP-A-167872 (both BASF AG).

In a catalyst which is particularly preferred here, the catalyticallyactive composition of the catalyst before treatment with hydrogencomprises from 25 to 65% by weight of aluminum oxide (Al₂O₃), from 30 to60% by weight of oxygen-comprising compounds of copper, calculated asCuO, and from 5 to 15% by weight of oxygen-comprising compounds ofnickel, calculated as NiO.

The temperature in the reactor which is preferred for the reaction ofdiethylene glycol (DEG) with ammonia is in this case in the range190-235° C. Preference is given to isothermal operation of the reactor.The pressure preferred for the reaction of diethylene glycol (DEG) withammonia is in the range from 20 to 30 bar.

The reaction of diethylene glycol. (DEG) with ammonia is preferablycarried out in the gas phase in the presence of hydrogen. The gaseousoutput from the reactor is preferably fed to a heat exchanger in which apartial condensation is preferably carried out (condensation of crudemorpholine). The gas phase comprising H₂ and NH₃ is preferably conveyedback to the DEG vaporizer and then into the reactor.

The process of the invention is particularly advantageous for preparingmorpholine (MO)

-   having a purity of ≧99.5% by weight, particularly preferably ≧99.6%    by weight, e.g. from 99.65 to 99.95% by weight,-   an N-ethylmorpholine (E-MO) content of ≦0.20% by weight,    particularly preferably ≦0.10% by weight, e.g. from 0.01 to 0.08% by    weight,-   a 1,2-ethylenediamine (EDA) content of ≦0.30% by weight,    particularly preferably ≦0.20% by weight, e.g. from 0.05 to 0.15% by    weight,-   a 2-methoxyethanol content of <0.50% by weight, particularly    preferably <0.30% by weight, e.g. from 0.05 to 0.25% by weight,-   and a water content of ≦0.05% by weight, particularly preferably    ≦0.04% by weight, e.g. from 0.01 to 0.03% by weight.

It is very particularly preferably advantageous for preparing morpholine(MO) having an APHA color number of ≦10, particularly preferably ≦8,e.g. from 2 to 7,

and a chloride content of ≦15 mg/liter, particularly preferably ≦5mg/liter, very particularly preferably ≦1 mg/liter, e.g. from 0.1 to 0.9mg/liter.

The process of the invention is also particularly advantageous forpreparing monoaminodiglycol (ADG) having a purity of ≧98.00% by weight,particularly preferably ≧98.30% by weight, e.g. from 98.50 to 99.50% byweight,

-   a DEG content of ≦0.40% by weight, particularly preferably ≦0.10% by    weight, e.g. from 0.01 to 0.08% by weight,-   a water content of ≦0.20% by weight, particularly preferably ≦0.10%    by weight, e.g. from 0.01 to 0.08% by weight,-   and an APHA color number of ≦20, particularly preferably ≦15, very    particularly preferably ≦10, e.g. from 2 to 8.

The process of the invention is also particularly advantageous forpreparing N-ethyl-morpholine (E-MO) having a purity of ≧98.50% byweight, particularly preferably ≧99.00% by weight, e.g. from 99.50 to99.90% by weight,

-   a water content of ≦0.30% by weight, particularly preferably ≦0.20%    by weight, e.g. from 0.05 to 0.15% by weight,-   and an APHA color number of ≦50, particularly preferably ≦20, very    particularly preferably ≦10, e.g. from 2 to 8.

APHA color numbers are determined in accordance with DIN EN 1557.

The water content is determined in accordance with DIN 51777 (K.Fischer).

The chloride content is determined by means of ion chromatography(detection of conductivity with chemical suppression), using thefollowing method:

Sample preparation: about 2 g of sample are weighed into a volumetricflask (10 ml) and made up to the mark with eluent.

Measurement conditions:

-   Ion chromatography system: Metrohm Modulares System (733)-   Preliminary column: e.g. DIONEX AG 12; separation column: e.g.    DIONEX AS 12-   Eluent: e.g. 2.7 mmol of Na₂CO₃, 0.28 mmol/l of NaHCO₃ in water-   Flow: 1 ml/min; injection volume: 100 μl-   Detection: conductivity after chemical suppression-   Suppressor: Metrohm Modul 753-   Regenerent: 50 mmol of H₂SO₄ in high-purity water (flow about 0.4    ml/min)-   Calibration: external, checked by standard addition experiments-   Determination limit: 0.1 mg/kg of chloride in the sample.

In the desired product morpholine, the content of morpholine,1,2-ethylenediamine, N-ethylmorpholine, 2-methoxyethanol is determinedby means of GC (GC conditions: 30 m DB-1; temperature program with 60°C. initial temperature, 4° C./min heating rate, 190° C. finaltemperature).

In the desired product ADG, the content of ADG and DEG is determined bymeans of GC (GC conditions: 30 m DB1, temperature program with 100° C.initial temperature, 8° C./min heating rate, 250° C. final temperature).

In the figures:

FIG. 1 shows, inter alia, the isolation of MO and ADG according to theinvention by means of a 6-column arrangement.

FIG. 2 shows, inter alia, the replacement of the columns K60-K70 of the6-column arrangement by a dividing wall column (DWC2).

FIG. 3 shows, inter alia, a particular embodiment of the dividing wallcolumn K60 in which the dividing wall (DW) extends to the bottom of thecolumn.

FIG. 4 shows, inter alia, the isolation of MO according to the inventionand an additional column (K80) for isolating ADG in particularly pureform.

FIG. 5 shows, inter alia, by way of example, the 6-column arrangement asused in the example, including recycle streams and synthesis part andheat integration (B1=high-pressure separator, B2=intermediate-pressureseparator, C1=reactor, V1=compressor, W1,2,3 and 4=heat exchangers).

FIG. 6 shows, inter alia, by way of example, an embodiment includingrecycle streams and synthesis part and heat integration in which thecolumns K60-K70 of the 6-column arrangement are replaced by a dividingwall column (DWC2).

FIG. 7 shows, inter alia, by way of example, an embodiment includingrecycle streams and synthesis part and heat integration in which thedividing wall (DW) extends to the bottom of the column.

HB=high boilers, LB=low boilers, IB=intermediate boilers, WWT=wastewaterrequiring treatment.

EXAMPLES Example 1 (see FIG. 5)

Diglycol (DEG) is mixed with the bottom product from the column K70(main components: diglycol and morpholyl-ADG) and the overhead productsfrom the columns K60 and K70 (main components: aminodiglycol,(2-aminoethyl)morpholine and 2-(2-aminoethoxy)ethylamine) and fedcontinuously to the heat exchanger W 1. Liquid ammonia is mixed withrecirculated ammonia from the column K10 and fed continuously to theheat exchanger W 1.

Both streams are mixed with the recycle gas consisting predominantly ofhydrogen upstream of the heat exchanger W 1. The recycle gas is broughtfrom the high-pressure separator B 1 located at the outlet from thesynthesis by means of the compressor V 1. After the heat exchanger W 1,the mixture which has a temperature of 140° C. is heated to 175° C. bymeans of a heater W 2 and conveyed to the reactor C 1.

The reaction of the diglycol to form aminodiglycol and morpholine takesplace over the fixed-bed catalyst there at a pressure of 200 bar andtemperatures up to 215° C. The output from the reactor is then cooled to45° C. in the heat exchangers W 1, W 3 and the air cooler W 4. In thehigh-pressure separator B 1, separation into a gas phase and a liquidphase occurs. The gas phase is, as described above, conveyed as recyclegas to the heat exchanger W 1.

The liquid phase from the high-pressure separator B 1 is depressurizedto 25 bar into the intermediate-pressure separator B 2. The gasliberated there from the effervescing liquid is conveyed into anabsorber to recover NH₃. The amount of hydrogen to be replaced is takenfrom the network and introduced into the feed to the synthesis.

The reaction mixture then goes from the intermediate-pressure separatorB 2 via the heat exchanger W 3 to the column K10.

Ammonia Removal (K10)

In the column K10, the ammonia is distilled off at a purity of >99.9%from the feed at a pressure at the top of 16 bar_(abs.)and recirculatedto the reactor inlet. The offgas is connected to an absorber. Theammonia-free bottoms having a temperature of 220° C. are depressurizedinto the column K20 for the removal of water. K10 has 17 theoreticalplates and the feed point is at plate 14.

Water Removal (K20)

In the column K20, the water of reaction is separated off at atmosphericpressure. The distillate, which comprises 98% by weight of water and 2%by weight of low boilers (predominantly ethylmorpholine), is fed to thecolumn K50. In addition, the overhead product of the pure morpholinedistillation K40 (main components: 1,2-ethylenediamine, morpholine andwater) is fed to the column K20. The largely water-free bottoms from K20are depressurized at a temperature of 158° C. (main components:morpholine, aminodiglycol, diglycol and high-boiling residue) into thecolumn K30. K20 has 56 theoretical plates and the feed point is at plate25.

Pure Morpholine Distillation (K30)

In the dividing wall column K30, morpholine (MO) having a concentrationof >99.6% by weight of morpholine and a 1,2-ethylenediamine (EDA)content of <0.10% by weight is separated off in gaseous form at a sideofftake in the lower third of the offtake part (3, 5), based on thenumber of theoretical plates of the offtake part, at a pressure at thetop of 550 mbar. The overhead distillate (main components:1,2-ethylenediamine, morpholine and water) is recirculated to K20 or,after concentration of ethylenediamine, discharged discontinuously via acontainer. The bottoms from the column K30 (main components:aminodiglycol, diglycol and high-boiling residue), which have atemperature of 217° C., are recirculated to the column K60.

The dividing wall column which has a dividing wall (DW) in thelongitudinal direction of the column has 33 theoretical plates in theupper combined column region (1), 6 theoretical plates in the lowercombined column region (6) and 21 theoretical plates in the inflow part(2, 4) and in the offtake part (3, 5). The bottoms from K20 are fed inin the upper third of the inflow part (2, 4) at plate 18 of 21 and MO isdischarged from the lower third of the offtake part (3, 5) at plate 9 of21.

Ethylmorpholine Distillation (K50)

In the column K50, N-ethylmorpholine is separated off from the feed asan azeotrope with water at atmospheric pressure. The bottoms from thecolumn, which have a temperature of 103° C., are discharged. K50 has 21theoretical plates and the feed point is at plate 11.

Residue Removal (K60)

In the column K60, aminodiglycol and diglycol are separated off togetherfrom the feed as a liquid side offtake stream at a pressure at the topof 60 mbar and are conveyed to the column K70. The distillate from thecolumn (main components: aminoethoxy-ethylamine, aminoethylmorpholine,aminodiglycol) is recirculated to the reactor inlet. The bottoms fromthe column, which have a bottoms temperature of 204° C., are dischargedfrom the process. K60 has 42 theoretical plates/feed point at plate20/side offtake at plate 36.

Aminodiglycol Distillation (K70)

In the column K70, aminodiglycol having a purity of >98.0% by weight anda water content <0.10% by weight is separated off from the feed as aliquid side offtake stream at a pressure at the top of 80 mbar. Thecondensate from the column (main components: aminodiglycol,(2-aminoethyl)morpholine and 2-(2-aminoethoxy)-ethylamine) isrecirculated to the reactor inlet. The bottoms from the column (87% byweight of DEG, 11% by weight of morpholyl-ADG and 2% by weight of highboilers), which have a bottoms temperature of 238° C., are likewiserecirculated to the reactor inlet. K70 has 42 theoretical plates, thefeed point is at plate 25 and the side offtake is at plate 35.

The numbering of the plates in the columns is from the bottom upward.

1. A process for the continuous fractional distillation of a mixturecomprising morpholine (MO), monoaminodiglycol (ADG), ammonia and waterfrom a reaction of diethylene glycol (DEG) with ammonia, the processcomprising: separating off ammonia from the mixture at a top of a firstdistillation column K10; feeding a bottom fraction from K10 to a seconddistillation column K20 in which water and organic products areseparated off at the top at a temperature at the top in the range from45 to 198° C. and a pressure in the range from 0.1 to 15 bar, feeding abottom fraction from K20 to a third distillation column K30, wherein thecolumn K30 is a dividing wall column (DWC) which preferably has adividing wall (DW) in the longitudinal direction of the column to forman upper combined column region (1), a lower combined column region (6),an inflow part (2, 4) having an enrichment section (2) and a strippingsection (4), and also an offtake part (3, 5) having an enrichmentsection (3) and a stripping section (5), with the bottoms from K20 beingfed in in the upper or middle third of the inflow part (2, 4), based onthe number of theoretical plates of the inflow part, ADG and organicproducts having a boiling point of >190° C. (1.013 bar) being dischargedat the bottom, organic products having a boiling point of ≦128° C.(1.013 bar) being discharged at the top and MO being discharged from themiddle or lower third of the offtake part (3, 5) (side offtake), basedon the number of theoretical plates of the offtake part.
 2. The processaccording to claim 1, wherein at least a portion of the organic productsseparated off at the top of column K30 are recirculated to the feed tothe column K20.
 3. The process according to claim 1, wherein the columnK10 has from 3 to 30 theoretical plates and is operated at a pressure of5 to 30 bar.
 4. A process according to claim 1 wherein the column K20has from 25 to 70 theoretical plates and is operated at a pressure of0.1 to 10 bar.
 5. The process according to claim 1, wherein the dividingwall column K30 has from 30 to 100 theoretical plates and is operated ata pressure of 0.01 to 5 bar.
 6. The process according to claim 1,wherein the feed point of column K10 is located in the upper third,based on the number of theoretical plates.
 7. The process according toclaim 1, wherein the feed point of column K20 is located in the middlethird, based on the number of theoretical plates.
 8. The processaccording to claim 1, wherein the subregion of the column (DWC) dividedby the dividing wall (DW) and comprising the subregions 2,3,4 and 5 orparts thereof is provided with order packing, random packing elementand/or trays and the dividing wall in these subregions is thermallyinsulating.
 9. The process according to claim 1, wherein the streamcomprising water and organic products which is separated off at the topof the column K20 is fed to a column K50 in which aqueousN-ethylmorpholine solution (aqueous E-MO solution) is separated off atthe top or at a side offtake for liquid and water is separated off atthe bottom.
 10. The process according to claim 9, wherein the column K50has from 10 to 50 theoretical plates and is operated at a pressure of0.01 to 16 bar.
 11. The process according to claim 9, wherein the feedpoint of column K50 is located in the upper or middle third, based onthe number of theoretical plates.
 12. The process according to claim 9,wherein the aqueous N-ethylmorpholine solution is dewatered and theorganic phase formed here is then concentrated by distillation to givethe desired product.
 13. The process according to claim 1, wherein thebottoms from K30 are fed to a distillation column K60 in wich ADG isseparated off at a side offtake, organic products having a boiling pointof ≦224.8° C. (1.013 bar) are separated off at the top and organicproducts having a boiling point of >255° C. (1.013 bar) are separatedoff at the bottom.
 14. The process according to claim 13, wherein thecolumn K60 has from 20 to 80 theoretical plates and is operated at apressure of 0.005 to 1 bar.
 15. The process according to claim 13,wherein the feed point of column K60 is located in the middle or lowerthird, based on the number of theoretical plates, and the ADG sideofftake located opposite the feed point is located from 1 to 30theoretical plates above the feed point.
 16. The process according toclaim 13, wherein organic products separated off at the top of thecolumn K60 are discharged or recirculated to the reaction of DEG withammonia.
 17. The process according to claim 13, wherein theADG-comprising stream separated off at the side offtake of the columnK60 is fed to a column K70 in which ADG is separated off at a sideofftake, organic products having a boiling point of ≧224.8° C. (1.013bar) are separated off at the bottom and organic products having aboiling point of ≦224.8° C. (1.013 bar) are separated off at the top.18. The process according to claim 17, wherein the column K70 has from10 to 80 theoretical plates and is operated at a pressure of 0.005 to 1bar.
 19. The process according to claim 17, wherein the feed point ofcolumn K70 is located in the upper or middle third, based on the numberof theoretical plates, and the ADG side offtake located opposite thefeed point is located from 1 to 30 theoretical plates above the feedpoint.
 20. The process according to claim 17, wherein products separatedoff at the bottom of column K70 are recirculated to the reaction of DEGwith ammonia.
 21. The process according to claim 17, wherein productsseparated off at the top of column K70 are recirculated to the reactionof DEG with ammonia.
 22. The process according to claim 13, wherein thecolumn K60 is a dividing wall column (DWC2).
 23. The process accordingto claim 22, wherein the dividing wall column (DWC2) has a dividing wall(DW) in the longitudinal direction of the column to form an uppercombined column region (1), a lower combined column region (6), aninflow part (2, 4) having an enrichment section (2) and a strippingsection (4), and also an offtake part (3, 5) having an enrichmentsection (3) and a stripping section (5), with the bottoms from K30 beingfed in in the upper or middle third of the inflow part (2, 4), based onthe number of theoretical plates of the inflow part, organic productshaving a boiling point of >255° C. (1.013 bar) being discharged at thebottom, organic products having a boiling point of ≦224.8° C. (1.013bar) being discharged at the top, ADG being discharged from the columnregion 1 and optionally gaseous organic products having a boiling pointof ≧224.8° C. (1.013 bar) being discharged from the upper or middlethird of the offtake part (3, 5) based on the number of theoreticalplates of the offtake part.
 24. The process according to claim 23,wherein products separated off in gaseous form at the side offtake arerecirculated to the reaction of DEG with ammonia
 25. The processaccording to claim 22, wherein the dividing wall column (DWC2) has adividing wall (DW) in the longitudinal direction of the column to forman upper combined column region (1) and (2), an inflow part (3, 4)having an enrichment section (3) and a stripping section (4), and also apart (5), with the dividing wall DW extending to the bottom of thecolumn and the bottoms from K30 being fed in in the upper or middlethird of the inflow part (3, 4), based on the number of theoreticalplates of the inflow part, DEG and organic products having a boilingpoint of ≧224.8° C. (1.013 bar) being discharged at the bottom below thepart 5, organic products having a boiling point of >255° C. (1.013 bar)being discharged at the bottom below the parts 3 and 4, organic productshaving a boiling point of ≦224.8° C. (1.013 bar) being discharged at thetop and ADG being discharged from the middle part of the upper combinedcolumn region (1) and (2).
 26. The process according to claim 25,wherein product separated off at the bottom below the part 5 arerecirculated to the reaction of DEG with ammonia.
 27. The processaccording to claim 22, wherein the dividing wall column K60 has from 30to 100 theoretical plates and is operated at a pressure of 0.005 to 1bar.
 28. The process according to claim 22, wherein the dividing wall isthermally insulating.
 29. The process according to claim 22, whereinorganic products separated off at the top are recirculated to thereaction of DEG with ammonia.
 30. The process according to claim 13,wherein at least a portion of the ADG-comprising stream separated off atthe top of the column K60 is fed to a column K80 in which ADG andorganic products having a boiling point of ≧224.8° C. (1.013 bar) areseparated off at the bottom and organic products having a boiling pointof ≦224.8° C. (1.013 bar) are separated off at the top.
 31. The processaccording to claim 30, wherein ADG is additionally separated off at aside offtake of the column K80.
 32. The process according to claim 30,wherein products separated off at the bottom of column K80 arerecirculated to the feed to the column K60.
 33. The process according toclaim 30, wherein products separated off at the top of column K80 aredischarged or recirculated to the reaction of DEG with ammonia.
 34. Theprocess according to claim 30, wherein the column K80 has from 10 to 80theoretical plates and is operated at a pressure of 0.005 to 3 bar. 35.The process according to claim 30, wherein the feed point of column K80is located in the upper or middle third, based on the number oftheoretical plates, and the ADG side offtake located opposite the feedpoint is located 1 to 30 theoretical plates below the feed point. 36.The process according to claim 1, wherein the mixture comprisesmorpholine, monoaminodiglycol, ammonia, water, N-ethylmorpholine,1,2-ethylenediamine and an organic product having a boiling pointof >224.8° C. (1.013 bar).
 37. The process according to claim 1, whereina morpholine product is obtained having a purity of ≦99.5 % by weight,an N-ethylmorpholine content of ≦0.20 % by weight, a 1,2-ethylenediaminecontent of ≦0.30 % by weight, a 2-methoxyethanol content of <0.50 % byweight and a water content of ≦0.05 % by weight.
 38. The processaccording to claim 1, wherein a morpholine product is obtained having anAPHA color number of ≦10 and a chloride content of ≦15 mg/liter.
 39. Theprocess according to claim 1, wherein a morpholine product is obtainedhaving a purity of ≧98.00 % by weight, a DEG content of ≦0.40 % byweight, a water content of ≦0.20 % by weight and an APHA color number of≦20.
 40. The process according to claim 1, wherein a morpholine productis obtained having a purity of ≧98.50 % by weight, a water content of≦0.30 % by weight and an APHA color number of ≦50.
 41. The processaccording to claim 1, wherein the mixture is produced by reaction ofdiethylene glycol with ammonia in the presence of a heterogeneouscatalyst wherein the catalyst comprises a) Cu, Ni or Co on a zirconiumdioxide support or b) Cu or Ni on an aluminum oxide support.